Prior art anatomical impressions in dentistry are utilized to make crowns and treatment trays for an individual patient. Typically, a tray is loaded with an alginate or polyvinyl siloxane substance and placed in a patient's mouth until it cures. Then the tray is removed and the impression used to make a cast of the patient's mouth. Until now, patients had to wait for the substance to cure before a true impression was made. The present invention departs from the prior art in that it utilizes a thermally set plastic, which can be imprinted and removed in moments. The present invention is also available for use with therapeutic plastics, thus directly creating a dental device for treatment of a patient.